Trophallaxis is the transfer of food or other fluids among members of a community through mouth-to-mouth (stomodeal) or anus-to-mouth (proctodeal) feeding. It is most highly developed in social insects such as ants, termites, wasps and bees. The word was introduced by the entomologist William Morton Wheeler in 1918.[1] The behaviour was used in the past to support theories on the origin of sociality in insects.[2] The Swiss psychologist and entomologist August Forel also believed that food sharing was key to ant society and he used an illustration of it as the frontispiece for his book The Social World of the Ants Compared with that of Man.[3]

In ants, individual colony members store food in their crops and regularly exchange it with other colony members and larvae to form a sort of "communal stomach" for the colony. In termites and cockroaches,[4] proctodeal trophallaxis is crucial for replacing the gut endosymbionts that are lost after every molt. This should not be confused with coprophagia. Some vertebrates such as birds and wolves also feed their young through trophallaxis.

Trophallaxis serves as a means of communication, at least in bees and ants. In some species of ants, it may play a role in spreading the colony odour that identifies members.[5]